The chalk particles embed themselves into the small pores on the surface.
Although a chalkboard seems smooth to the touch, it is quite rough at the microscopic level, with <em>pores</em> that reach below the surface.
When you drag chalk across the board, friction causes small particles of chalk to rub off onto the surface.
If you leave the markings for a long time, some of the chalk particles will work their way into the pores.
A brush will remove the surface particles, but <em>it will not be able to get at the particles in the pores</em>.
Answer:
1000 g
Explanation:
d = m/v
We are given d: 10g/cm3
and v: 100cm3
Plug them into the equation to get 10 = m/100
Then, cross multiply 10x100 to get mass which is: 1000g
<span>An element is made of only one kind of atom, while a compound contains the atoms of two or more elements. For example, gold is made of only one kind of atom, so it is an element, but water is a mix of hydrogen and oxygen, so it is a compound.</span>
Sc(21), Cr(24), Fe(26), Zn(30)
